Dilatable banding of a Blalock-Taussig shunt

Surgical outcomes of the systemic-to-pulmonary artery shunt: risk factors of post-operative acute events and effectiveness of regulation of pulmonary blood flow with metal clips

OBJECTIVES

The aim of this study was to analyze the risk factors for acute events after systemic-to-pulmonary shunt (SPS) and to investigate the effectiveness of pulmonary blood flow regulation with a metal clip.

METHODS

The case histories of 116 patients (78 biventricular [BV] and 38 single ventricle [SV] physiology) who underwent SPS between 2010 and 2021 were retrospectively reviewed. Our strategy was to delay SPS until 1 month of age; pulmonary blood flow (PBF) regulation by partial clipping of the graft, if needed. Cases of aortic cross-clamping were excluded from this study.

RESULTS

CPB was used in 49 (42%) patients: the median age at SPS was 1 month (2 days to 16 years), and the sternotomy approach in 65. Discharge survival was 98.3% (114/116); hospital death occurred in 1.7% due to coronary ischemia. Inter-stage mortality occurred in 1.7% (shunt thrombosis, 1; pneumonia, 1). Pre-discharge acute events occurred in 7 patients (6.0%): thrombosis 3, pulmonary over-circulation 2, and coronary ischemia 2. Multiple logistic regression analysis revealed that pulmonary atresia with intact ventricular septum (PA/IVS) (p = 0.0253) was an independent risk factor for acute events. Partial clipping of the graft was performed in 24 patients (pulmonary atresia 15) and clip removal was performed by catheter intervention in 9 patients; no coronary ischemic events and graft injury occurred in these patients.

CONCLUSION

Surgical outcomes after SPS were acceptable and metal clip regulation of pulmonary blood flow appears to be safe and effective. PA/IVS was still a significant risk factor for acute events.

Expandable Valves, Annuloplasty Rings, Shunts, and Bands for Growing Children

In congenital heart surgery, the surgeon must constantly consider how a palliative or corrective procedure could be impacted by the child's somatic growth. Within pediatric valve surgery, existing valve repair techniques lack growth-accommodating prostheses. Valve replacement options are fixed in size and unable to grow with the child, thus subjecting children to repeated valve reoperations. When creating a systemic-to-pulmonary artery shunt, replacing a branch pulmonary artery or conduit, creating an extracardiac Fontan pathway, or banding the pulmonary artery, the implant size must factor in both the child's current size and his or her anticipated growth. A variety of growth-accommodating technologies have been developed to fill this unmet need. Some devices have reached the clinical arena, while several are in preclinical development. The purpose of this review is to characterize the clinical need for growing device technology, and then review established and developing technologies for growth accommodation in congenital heart surgery.

Balancing pulmonary blood flow: Theory, in vitro measurements, and clinical correlation of systemic-to-pulmonary shunt banding

BACKGROUND

Size mismatch between body and a systemic-to-pulmonary shunt can result in excessive pulmonary blood flow, compromising systemic oxygen delivery. Previously reported techniques to mechanically restrict shunt flow lack precision and reproducibility. We developed a formula for shunt banding and assessed its efficacy and reproducibility by in vitro and clinical measurements.

METHODS

Formulas to determine diameter reduction, length of banding, and effect on the ratio of pulmonary blood flow (Q_p) to systemic blood flow (Q_s) were established. In vitro measurements of different shunt grafts were performed. Results were compared with calculations and clinical data. Clinical outcome was retrospectively assessed in all patients (n = 8) who underwent a shunt banding procedure at our institution between 2008 and 2012.

RESULTS

Our formulas can adequately predict the length of the band based on the desired diameter and shunt type or on the Q_p:Q_s mismatch. In vitro measurements correlated with the manufacturer's specifications in small shunts (≤5 mm diameter; 0.45 mm mean wall thickness). The calculated diameters of these shunts were closely correlated with in vitro measurements (r = 0.953; P = .001). Arterial saturation, pH, and calculated Q_p:Q_s decreased significantly with banding (P = .026, .002, and .004, respectively). Clinical effects varied among patients, with hemodynamically stable patients achieving the most benefit. Adjustment of the band was required in 1 patient. No shunt thrombosis or shunt banding-related complications were noted.

CONCLUSIONS

Our formulas and surgical strategy offer a new approach to controlling excessive pulmonary blood flow in shunt-dependent circulations in an effective and predictable way. The best reproducibility was achieved in small, thin-walled shunts. This strategy was most effective in patients with pulmonary overcirculation without hemodynamic decompensation.

Accordion-like prosthesis for modified Blalock-Taussig shunt

From March 1996 to July 2002, 26 consecutive patients, with a mean age of 17.9 months and a mean body weight of 6.6 kg, underwent the modified Blalock-Taussig shunt with a tubular accordion-like prosthesis. In a mean follow-up period (defined as the interval between the shunt procedure and repair or last evaluation) of 10.9 months (range, 1 to 32 months), there were 1 death due to excessive pulmonary blood flow in a neonate with hypoplastic left heart syndrome and 3 reoperations to correct shunt-related problems, 2 of them early and 1 late (to regulate pulmonary blood flow after left ventricular retraining for transposition of the great arteries). There was no occurrence of shunt obstruction or kinking. Other shunt-related early complications, such as bleeding, infection, or serous fluid leakage, did not occur, and no patient needed pulmonary artery reconstruction during surgical repair. Shunt patency was confirmed by Doppler echocardiography in all patients and also by angiography in 73% of the patients. This prospective study confirmed our preliminary results with this prosthesis. The use of this prosthesis is justified for reducing early and late complications potentially associated with the modified Blalock-Taussig shunt, particularly distortion of the pulmonary arteries.